Inorganic nitrites, especially sodium nitrite, are employed in the manufacture of numerous chemical compounds, e.g., diazo dyes, and are used in printing of textile fabrics and bleaching of various fabrics. It is desirable to obtain these nitrites with a low percentage of corresponding nitrate. The present invention is directed to obtaining such a nitrite.
Although it was disclosed in a general sense as long ago as 1907 in U.S. Pat. No. 871,640 that the proportion of nitrites to nitrates produced could be kept high by holding the mixed nitrogen oxide gases at high temperatures, such as over 300.degree. C., until they are absorbed in caustic media; more recent patents such as U.S. Pat. No. 2,797,144 still do not provide means for as selective a production of nitrites as is desirable. The latter patent suggests that the gases should be kept hot enough to prevent the condensation of highly corrosive aqueous condensates. However, further improvements in nitrite production are desirable and can be sought through process and equipment modification.